A data bus can be utilized for interconnecting digital electronic devices such as television receivers, display devices, video-cassette recorders (VCR), direct broadcast satellite (DBS) receivers, and home control devices (e.g., a security system or a temperature control device). Communication using a data bus occurs in accordance with a bus protocol. Examples of bus protocols include the Consumer Electronics Bus (CEBus) and the IEEE 1394 High Performance Serial Bus.
A bus protocol typically provides for communicating both control information and data. For example, CEBus control information is communicated on a “control channel” having a protocol defined in Electronics Industries Association (EIA) specification IS-60. On an IEEE 1394 serial bus, control information is generally passed using the asynchronous services of the serial bus. Control information for a particular application can be defined using for example, Common Application Language (CAL) or AV/C.
In today's analog audio/video (A/V) cluster, controlling peripheral devices may include, but do not require, the activation of an On-Screen Display (OSD) mechanism on a display device (i.e., TV). The OSD of such A/V devices is generated in the peripheral or target device (e.g., VCR) and is output on the NTSC output of such devices the same way as any other video signal. Thus, no additional hardware or software is needed in either the peripheral or the display device. FIG. 1 illustrates a present A/V system 10 having a VCR 12 and a display device 14 (e.g., television) that employs such a control methodology. Menus associated with controlling VCR 12 are generated by the VCR 12 and are provided to the display device 14 via the NTSC output of the VCR 12 as a composite video signal.